Abstract
The movements of cilia in tracheal and sinus mucosa were recorded photoelectrically. the following results were achieved. In vitro activity (1) ceased rapidly in an anoxic environment and swelling and deformations of cilia were seen (SEM), (2) was normal in rabbit tracheae in pO2∼20 kPa but impaired in pO2∼10 kPa and less, and (3) was normal on rabbit sinus mucosa in pO2∼1 kPa. In vivo activity in the opened maxillary sinus of anesthetized rabbits was (1) resistant to low pO2 as well as high pCO2 in ambient atmosphere (2) resistant to low pO2 and high pCO2 of arterial blood but (3) retarded (luring simultaneous low pO2 and high pCO2 in ambient atmosphere and arterial blood.